The Brazilian trio were on the plane with the rest of the Blues squad ahead of their charity tournament tomorrow.
Chelsea will take part in the friendly event by playing two 45-minute matches, one against Fenerbahce, where former midfielder Raul Meireles plays, and one against Besiktas, Demba Ba's new home.
Then, on Sunday, the Blues will face Ferencvaros in a 90-minute friendly.
It appears Willian, who was signed from Anzhi for £30 million last term, will take part in at least one of Chelsea's matches, while Ramires and Oscar are likely to also see action ahead of their Premier League opener at Burnley.
Speculation has been rife about Ramires' Stamford Bridge future this summer, although no reports of late have suggested any concrete bids for the midfielder.
As things stand, the 27-year-old will be as much a Chelsea player as his Brazilian team-mates this season, with Oscar and Willian likely to play a prominent role in the club's campaign.
The arrival of Cesc Fabregas has increased the competition for places within Mourinho's midfield, though it seems the 'Special One' is happy to maximise the number of options available to him as he looks to challenge on all four fronts with greater vigour this term.
This week's trip to Turkey could help him decide who to use to kick-start Chelsea's season.